1. Field of the Invention
The subject invention relates to an apparatus for preventing the spread of fires in buildings, and more particularly, to fire resistant enclosures for recessed fixtures, such as, for example, lighting fixtures, as well as methods of fabricating and installing the same.
2. Background of the Related Art
In residential and commercial buildings it is commonplace to provide insulation materials between ceiling joists to reduce heat loss from the living spaces. It is also commonplace to install recessed fixtures, such as, for example, lighting fixtures and loudspeaker units, in the living spaces which include portions that extend through the ceiling between the ceiling joists. A typical twenty unit condominium building can have hundreds of recessed lighting fixtures.
It is well known that during use, recessed fixtures, and in particular recessed lighting fixtures tend to generate a significant amount of heat, and because some insulating materials unitized in residential buildings are combustible, a fire hazard generally exists. The Uniform Building Code (U.B.C.) requires that openings or penetrations for recessed lighting fixtures in all wood framed ceiling assemblies must be protected by a penetration firestop system. Such a system must limit the spread of fire, flame or hot gases through the firestop assembly for an acceptable period of time, when tested in accordance with the time-temperature curve provided in U.B.C. Standard 7-1, which is herein incorporated by reference.
There have been attempts in the prior art to provide fire rated enclosures which isolate recessed fixtures, such as lighting and speaker units, from combustible insulation materials so as to reduce the risk of fire, and which conform with applicable building codes to prevent the spread of fire. For example, it is known in the construction industry to build a sheet rock enclosure around a recessed lighting fixture to isolate the fixture from insulation materials, and to provide a suitable firestop system for the ceiling penetration. To accomplish this, the joist space in which the lighting fixture is to be installed must first be blocked by a carpenter so that the joists can carry the sheet rock enclosure. The sheet rock is then attached to the joists and sealed. This prior art method is extremely labor intensive and very costly.
An example of an insulation barrier constructed from a plurality of panels fabricated from a fire-proof material such as Portland cement reinforced with asbestos fibers, and joined together by clips is disclosed in U.S. Pat. No. 4,237,671 to Munson. The prefabricated panels are dimensioned to accomodate different joist spacings, but they must be constructed at the building site for utilization. Examples of preformed insulation barriers constructed from aluminum sheet metal are disclosed in U.S. Pat. No. 4,375,142 to McDonald and U.S. Pat. No. 4,400,766 to Munson. Both of these devices include perforations to facilitate construction, and therefore they do not provide a firestop system which conforms with applicable building codes. Furthermore, aluminum sheet metal is a relatively expensive material, and its usage adds significantly to the cost of construction. Clearly, there is a need in the art for an inexpensive preformed insulation barrier which conforms with the firestop requirements of applicable building codes.